So you've installed Mountain Lion with the all new Notification Center. Good for you!
But what's this? All those old Growl notifications mixed with the shiny and new. Doesn't seem right, eh?

Other solutions like Hiss are okay, but a actually a weird hack with a lot of down sides. So while waiting for Growl 2 (which hopefully will support the Notification Center) why not use the current Growl with a plugin that does the necessary. All as a 1st class citizen in Growl.

One of the upsides of OS X Mountain Lion's already low purchase price of $20 is that one copy can be re-downloaded and installed on any other Macs that you own for free. The downside, of course, is that if another Mac in the household doesn't share the same Apple ID as you, the buyer, you have to get another copy. As it turns out, there's a very simple solution so you can just reinstall from the same copy as many times as you need to.

Lion Disk Maker is an application programmed with AppleScript that you can use with Mac OS X 10.6, 10.7 and OS X 10.8 to burn a DVD or build a bootable drive from Mac OS X Lion or OS X Mountain Lion Installation program. As soon as you launch the application, it tries to find the OS X Install program with Spotlight. Then, it proposes to build a DVD or create a bootable install disk. It’s the easiest way to build an OS X Installer in a few clicks !

Lion Disk Maker is an application programmed with AppleScript that you can use with Mac OS X 10.6, 10.7 and OS X 10.8 to burn a DVD or build a bootable drive from Mac OS X Lion or OS X Mountain Lion Installation program. As soon as you launch the application, it tries to find the OS X Install program with Spotlight. Then, it proposes to build a DVD or create a bootable install disk.